Category Archives: Parsha

Aerodynamics of Egyptian Hail

Something About Sforno  — A Short Dvar Torah on the Parsha — Va’era 5769

Aerodynamics of Egyptian Hail

US Air Force test pilot, Chuck Yeager, is credited as being the first person to break the sound barrier on October 14, 1947, in the Bell X-1. Many pilots before him died trying. It took test pilots and engineers many years to understand and overcome the many issues surrounding traveling faster than the speed of sound. Some scientists thought it was impossible and aircraft would break apart from the extreme pressure and vibrations as they approached the sound barrier.

In the early days of the cold war, the one critical element lacking in the development of nuclear missiles was known as “atmospheric reentry technology”. Scientists discovered that anything they sent into space or even the upper atmosphere would burn up on reentry. As such they needed to develop proper shielding technology to protect the “payload”.

Sonic booms and atmospheric reentry burnout were technological issues that were not even dreamed off until a few decades ago.

As such, it is outright incredible that Rabbi Ovadia Sforno describes both of these phenomena in his commentary about half a millennium ago.

In Exodus 9:23-24 the Bible recounts:

“And Moses outstretched his staff to the heavens, and God gave sounds and hail, and fire descended earthward, and God rained down hail upon the land of Egypt. And there was hail and fire together in the hail, very heavy, the like of which was not in Egypt since it’s becoming a nation.”

Sforno comments on the “fire descended”:

“The flaming air descended to the earth with the force of the movement of the hail that pressed on it (the air) during its descent.”

Sforno basically and accurately described atmospheric reentry during the same period of time when Leonardo Da Vinci was playing with his water engine.

Sforno continues:

“In the force of the movement of the hail during its descent, the air was flamed and produced sound.”

He’s talking about sonic booms!

Imagine an ongoing downpour of burning hailstones accompanied by continuous sonic booms. It’s no wonder Pharaoh is frightened out of his wits and begs for the noise to stop before mentioning the hail.

The fact that Sforno was able to describe scientific concepts that we think of as exclusively from our modern era simply leaves me awestruck.

May plagues continue to hail down on our enemies, and may we be spared, and like our ancestors may we witness redemption.

Shabbat Shalom,

Bentzi

Dedication

To the memory of Dr. Irwin Rochwarger, a beloved mentor and teacher. As an engineer who designed and built satellites for NASA, amongst many other amazing technological feats, he would have appreciated very much Sforno’s insight.

Unfamiliar Terms?


http://en.wikipedia.org/wiki/Sonic_boom

The term sonic boom is commonly used to refer to the shocks caused by the supersonic flight of an aircraft. Sonic booms generate enormous amounts of sound energy, sounding much like an explosion. Thunder is a type of natural sonic boom, created by the rapid heating and expansion of air in a lightning discharge.[1]

Causes

When an object passes through the air, it creates a series of pressure waves in front of it and behind it, similar to the bow and stern waves created by a boat. These waves travel at the speed of sound, and as the speed of the object increases, the waves are forced together, or compressed, because they cannot “get out of the way” of each other, eventually merging into a single shock wave at the speed of sound. This critical speed is known as Mach 1 and is approximately 1,225 kilometers per hour (761 mph) at sea level.

Bullwhip

The cracking sound a bullwhip makes when properly wielded is, in fact, a small sonic boom. The end of the whip, known as the “cracker”, moves faster than the speed of sound, thus resulting in the sonic boom.[3] The whip was the first human invention to break the sound barrier.[citation needed]

A bullwhip tapers down from the handle section to the cracker. The cracker has much less mass than the handle section. When the whip is sharply swung, the energy is transferred down the length of the tapering whip. In accordance with the formula for kinetic energy, the velocity of the whip increases with the decrease in mass, which is how the whip reaches the speed of sound and causes a sonic boom.

The Diamond in the Cesspool

Something About Sforno  — A Short Dvar Torah on the Parsha — Shmot 5769

The Diamond in the Cesspool

The Egypt of our ancestors was apparently one of great moral depravity. Egyptian culture was submerged in a superficial, materialistic, hedonistic, idol worshipping, incestuous reality. A by-product of such a society was many unwanted births and a cheapening of life.

In the beginning of the Book of Exodus, the Children of Israel have evolved from honored guests and royal protégés, to feared enemies and eventually downtrodden slaves. The low point of this progression is perhaps the draconian edict to kill all newborn Jewish boys.

Into this environment Moses is born. Fearing for his life, the mother of Moses takes the desperate measure of placing the three-month old into a basket to float on the river. Moses’ sister, not without hope, keeps an eye on the basket (Exodus 2).

Pharaoh’s daughter spots Moses’ basket while bathing in the Nile. She investigates and is surprised to find baby Moses within.

At this point Rabbi Ovadia Sforno asks as to why Pharaoh’s daughter would claim Moses. Sforno explains that it was apparently common practice for Egyptians to discard unwanted children into the river, and there would be a plethora of abandoned children to be claimed.

Sforno answers that the “goodness” of Moses was “shinning” and was clearly visible for anyone to see. Pharaoh’s daughter said to herself: “This is not some bastard or unwanted child. This is a beautiful Israelite child. He is so stunningly gorgeous that I must claim him for myself.”

Sforno continues to explain that Moses was visibly outstanding because of the “ingredients” put into him. Following is a translation of Sforno’s comment regarding the reaction to the birth of Moses by his mother, that “he was good”:

“She noted that he was more beautiful than normal, and thought that this was for an intended purpose from his Creator, for the beauty of the form indicates the quality of the ingredients and the complete power of the Designer.”

As we all know, Moses was indeed intended for supreme greatness, even amidst the decadence and immorality of Egyptian culture.

May we all transcend the negative environments around us, and like Moses, take the great ingredients that are a part of us – and shine.

Shabbat Shalom,

Bentzi

Dedication

To the recovery of 2nd Lieutenant Aharon Karov of the IDF Paratrooper Brigade. Aharon is from the community of Karnei Shomron. He left to Gaza the morning after his wedding to lead his soldiers. He was critically injured from a blast within a booby trapped home in Northern Gaza. Please pray for him – Aharon Yehoshua ben Chaya Shoshana. May our soldiers be safe, may the wounded recover and may the mourners be comforted.

Unfamiliar terms?

Drawn from Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Nile

The Nile is a major north-flowing river in Africa, generally regarded as the longest river in the world.[1]

The northern section of the river flows almost entirely through desert, from Sudan into Egypt, a country whose civilization has depended on the river since ancient times. Most of the population of Egypt and all of its cities, with the exception of those near the coast, lie along those parts of the Nile valley north of Aswan; and nearly all the cultural and historical sites of Ancient Egypt are found along the banks of the river. The Nile ends in a large delta that empties into the Mediterranean Sea.

The Nile (iteru in Ancient Egyptian) was the lifeline of the ancient Egyptian civilization, with most of the population and all of the cities of Egypt resting along those parts of the Nile valley lying north of Aswan. The Nile has been the lifeline for Egyptian culture since the Stone Age. Climate change, or perhaps overgrazing, desiccated the pastoral lands of Egypt to form the Sahara desert, possibly as long ago as 8000 BC, and the inhabitants then presumably migrated to the river, where they developed a settled agricultural economy and a more centralized society.

Sustenance played a crucial role in the founding of Egyptian civilization. The Nile is an unending source of sustenance. The Nile made the land surrounding it extremely fertile when it flooded or was inundated annually. The Egyptians were able to cultivate wheat and crops around the Nile, providing food for the general population. Also, the Nile’s water attracted game such as water buffalo; and after the Persians introduced them in the 7th century BC, camels. These animals could be killed for meat, or could be captured, tamed and used for ploughing — or in the camels’ case, travelling. Water was vital to both people and livestock. The Nile was also a convenient and efficient way of transportation for people and goods.

The structure of Egypt’s society made it one of the most stable in history. In fact, it might easily have surpassed many modern societies. This stability was an immediate result of the Nile’s fertility. The Nile also provided flax for trade. Wheat was also traded, a crucial crop in the Middle East where famine was very common. This trading system secured the diplomatic relationship Egypt had with other countries, and often contributed to Egypt’s economic stability. Also, the Nile provided the resources such as food or money, to quickly and efficiently raise an army for offensive or defensive roles.

The Nile played a major role in politics and social life. The pharaoh would supposedly flood the Nile, and in return for the life-giving water and crops, the peasants would cultivate the fertile soil and send a portion of the resources they had reaped to the Pharaoh. He or she would in turn use it for the well-being of Egyptian society.

The Nile was a source of spiritual dimension. The Nile was so significant to the lifestyle of the Egyptians, that they created a god dedicated to the welfare of the Nile’s annual inundation. The god’s name was Hapy, and both he and the pharaoh were thought to control the flooding of the Nile River. Also, the Nile was considered as a causeway from life to death and afterlife. The east was thought of as a place of birth and growth, and the west was considered the place of death, as the god Ra, the sun, underwent birth, death, and resurrection each time he crossed the sky. Thus, all tombs were located west of the Nile, because the Egyptians believed that in order to enter the afterlife, they must be buried on the side that symbolized death.

The Greek historian, Herodotus, wrote that ‘Egypt was the gift of the Nile’, and in a sense that is correct. Without the waters of the Nile River for irrigation, Egyptian civilization would probably have been short-lived. The Nile provided the elements that make a vigorous civilization, and contributed much to its lasting three thousand years.